Effect of Post-Cesarean Delivery Oral Cephalexin and Metronidazole on Surgical Site Infection Among Obese Women: A Randomized Clinical Trial

JAMA. 2017 Sep 19;318(11):1026-1034. doi: 10.1001/jama.2017.10567.


Importance: The rate of obesity among US women has been increasing, and obesity is associated with increased risk of surgical site infection (SSI) following cesarean delivery. The optimal perioperative antibiotic prophylactic regimen in this high-risk population undergoing cesarean delivery is unknown.

Objective: To determine rates of SSI among obese women who receive prophylactic oral cephalexin and metronidazole vs placebo for 48 hours following cesarean delivery.

Design, setting, and participants: Randomized, double-blind clinical trial comparing oral cephalexin and metronidazole vs placebo for 48 hours following cesarean delivery for the prevention of SSI in obese women (prepregnancy BMI ≥30) who had received standard intravenous preoperative cephalosporin prophylaxis. Randomization was stratified by intact vs rupture of membranes prior to delivery. The study was conducted at the University of Cincinnati Medical Center, Cincinnati, Ohio, an academic and urban setting, between October 2010 and December 2015, with final follow-up through February 2016.

Interventions: Participants were randomly assigned to receive oral cephalexin, 500 mg, and metronidazole, 500 mg (n = 202 participants), vs identical-appearing placebo (n = 201 participants) every 8 hours for a total of 48 hours following cesarean delivery.

Main outcomes and measures: The primary outcome was SSI, defined as any superficial incisional, deep incisional, or organ/space infections within 30 days after cesarean delivery.

Results: Among 403 randomized participants who were included (mean age, 28 [SD, 6] years; mean BMI, 39.7 [SD, 7.8]), 382 (94.6%) completed the trial. The overall rate of SSI was 10.9% (95% CI, 7.9%-14.0%). Surgical site infection was diagnosed in 13 women (6.4%) in the cephalexin-metronidazole group vs 31 women (15.4%) in the placebo group (difference, 9.0% [95% CI, 2.9%-15.0%]; relative risk, 0.41 [95% CI, 0.22-0.77]; P = .01). There were no serious adverse events, including allergic reaction, reported in either the antibiotic group or the placebo group.

Conclusions and relevance: Among obese women undergoing cesarean delivery who received the standard preoperative cephalosporin prophylaxis, a postoperative 48-hour course of oral cephalexin and metronidazole, compared with placebo, reduced the rate of SSI within 30 days after delivery. For prevention of SSI among obese women after cesarean delivery, prophylactic oral cephalexin and metronidazole may be warranted.

Trial registration: clinicaltrials.gov Identifier: NCT01194115.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Adult
  • Anti-Bacterial Agents / therapeutic use*
  • Antibiotic Prophylaxis*
  • Cephalexin / therapeutic use*
  • Cesarean Section / adverse effects*
  • Double-Blind Method
  • Drug Therapy, Combination
  • Female
  • Humans
  • Metronidazole / therapeutic use
  • Obesity / complications*
  • Postoperative Care
  • Surgical Wound Infection / prevention & control*


  • Anti-Bacterial Agents
  • Metronidazole
  • Cephalexin

Associated data

  • ClinicalTrials.gov/NCT01194115
  • ClinicalTrials.gov/NCT01194115